Metering pump

ABSTRACT

This application discloses a pumping and metering device wherein such pumping and metering functions are accomplished by drawing a continuous member through a passageway which changes in crosssectional area. A series of cavities between the bore and the continuous member are provided with resiliently deformable means so that the cavities change in volume as the continuous member moves through the transitionary section of bore cross-sectional area where fluid may be metered into or out of the cavities.

Emited States Patent Lofquist, Jr. Dec. 9, 1975 4] METERING PUMP 2,510,657 6/1950 Rapisarda 417/320 3,148,624 9/1964 Baldwin 417/383 [76] Invent 3 i gi 10 3,365,104 1/1968 Bowman 222/365 nn a, a1 FOREIGN PATENTS OR APPLICATIONS [2221 Flled May 1973 2,632 4/1866 United Kingdom 417/320 [21] Appl. No.: 357,682

Prima ExaminerWilliam L. Freeh [44] Pubhshed under the Trial Voluntary Protest ry Program on January 28 1975 as document no. Attorney, Agent, or FirmL1mbach, Llmbach & B 357,682. Sutccn Related US. Application Data [57] ABSTRACT [63] Continuation-impart of Ser. No. 338,103, March 5,

1973 This applicatlon d1scl0ses a pumping and metering device wherein such pumping and metering functions are 52 us. (:1. 417/320 accomplished by drawing a ccminucuc mcmbcr 51 1m.c1. F04B 19/14; FOlD 23/00; FO3B 9/00 thrccgh a P Y Y which changcc crcss- [58] Field of Search 222/371, 365; 417/321 sect1onal area. A series of cavlties between the bore 417/320, 479 550; 415/5; 198/129 and the continuous member are provided with resil- 153, 193; 92/90, iently deformable means so that the cavities change in volume as the continuous member moves through the [56] References Cited transitionary section of bore cross-sectional area UNTED STATES PATENTS where fluid may be metered into or out of the cavities. 1,382,705 6/1921 Wood 417/489 12 Claims, 7 Drawing Figures U.S. Patsnt Dec. 9, 1975 Sheet 1 0f 3 3,924,973

FIG!

FIG. 3

US. Patent Dec. 9, 1975 Sheet 2 of3 3,924,973

'IIIIIII' I J I US. Patent Dec. 9, 1975 Sheet 3 of3 3,924,973

FIG. 6

METERING PUMP RELATED APPLICATION This is a continuation-in-part of my co-pending application Ser. No. 338,103, filed Mar. 5, 1973.

BACKGROUND OF THE INVENTION This invention relates generally to improvements in the design and construction of positive displacement pumps and metering devices, and more specifically to the incorporation of a succession of axially aligned bores of varying diameters or cross-sectional areas through which a continuous member with annular elements is drawn to achieve a pumping action.

In accordance with this invention, a continuous or endless member such as a cable or flexible rod fitted at regular intervals with annular elements will define a volume when drawn through a bore in a block of material, the diameter of such bore being greater than the diameter of the cable but less than the diameter of the annular elements so as to form a fluid seal between the annular elements and the wall of the bore. The volume defined between any two successive annular elements is 7T(R R (P) V, where R and R are the radii of the bore and the cable respectively, P is the pitch or longitudinal distance between annular elements, and V is the volume of one annular element surrounding the cable, such volume varying depending upon the configuration of the annular element and the material of construction of both the element and the cable. When the same cable with annular elements is drawn through a bore of different diameter, a different volume will be defined. The difference between the volumes defined when the cable with annular elements is drawn through a succession of axial bores of differing diameters in a block of material is the net volume of fluid pumped or metered. When the cable is drawn in the direction from the larger to the smaller diameter bore fluid is discharged; when the cable is drawn in the direction from the smaller to the larger diameter bore fluid is drawn in to the process.

In the preferred form of the invention as shown in the drawings, the annular elements located along the cable or rod are of such material to permit deformation due to bending and compression in order to conform to and form a seal with the rigid walls of the cylindrical bore, and to accomodate the further deformation necessary to traversing from a bore of one diameter or cross-sectional area to a bore of a smaller diameter or cross-sectional area.

In other forms of the invention, the annular elements and cable or rod may be of essentially rigid construction, but with the walls of the cylindrical bore being of compressible material to accomodate and permit the passage of annular elements with a diameter greater than the inside diameter of the bore. An extension of this form of the invention includes a section of compressible bore wall being in the form of flexible tubing having a supported cavity between the tubing and the block of material forming the pump housing, into which cavity a hydraulic fluid may be inserted to deform the tubing and reduce the inside diameter of the bore and to thereby change the volume of fluid being pumped or metered. Other means than hydraulic pressure may also be used to change the inside diameter of the section of the bore.

In still other forms of this invention, a series of pump elements may be connected in parallel or series arrangements to achieve such specific operating advantages as the pre-compression of a compressible fluid prior to the final metering or pumping function.

The principal object of this invention is to provide a pumping device capable of achieving an extremely small flow of fluids.

A more specific object of this invention is to provide a pumping device with a discharge that is essentially free of the pulsations normally associated with small volume metering pumps.

It is another object of this invention to provide a metering pump with a minimum of operating elements, and particularly a pump that does not require such additional elements as check valves for its satisfactory operation.

It is another object of the invention to provide a simple metering device consisting of a series of moving pockets with means for changing the volume of the pockets so that fluid can be pulled into the pockets or expelled from the pockets or both, and the change in pocket volume can be very small. The device can be used simply for conveying or metering fluids to and from external devices or the device can be used for metering small volumes of reagents into the device for conducting analyses on samples contained in the pockets.

Other objects and advantages of the invention will become apparent upon full consideration of the following description and attached drawings in which:

FIG. 1 is a sectional view through one preferred embodiment of the metering pump according to the invention having compressible balls as the annular elements on a cable being continuously drawn through a stepped diameter bore in a rigid material.

FIG. 2 is a sectional view through another embodiment of the continuous member with annular elements and pumping block portion of the metering pump according to this invention.

FIG. 3 is a sectional view through yet another embodiment of the pumping block and continuous member with annular elements of the metering pump according to the present invention in which the annular elements and continuous cable are of essentially noncompressible materials, and the stepped axial bore in the pumping block is through a compressible material arranged within a rigid and adjustable pumping block housing to facilitate changing the inside diameter of the axial bore.

FIG. 4 is a sectional view through a further preferred embodiment of the pumping block and continuous member with annular elements of the metering pump according to this invention in which deformable annular rings mounted on a flexible continuous rod are drawn through a stepped diameter axial bore, one section of which is fitted with a deformable sleeve and provision for changing the inside diameter of the bore and therefore the volume of fluid to be pumped.

FIG. 5 is a sectional and diagramatic view of yet a further preferred embodiment of the metering pump according to this invention in which two pumping blocks are operated in series with a common continuous rod with annular elements, and with a pressure controlled flow control valve, to achieve the pre-compression of compressible fluids to permit the consistent volumetric or mass metering of the fluid to process under varying discharge pressure conditions.

FIG. 6 is a sectional view through still another preferred embodiment of the pumping block and continuous member with annular elements of the metering pump according to this invention in which an arrangement of various diameter axial bores in conjunction with a continuous member with deformable annular elements enables fluid to be carried into the pumping block from the pump housing cavity to be mixed with another fluid drawn into the pumping block and then this mixture subsequently discharged from the pumping block.

FIG. 7 is a sectional view through still a further preferred embodiment of the pumping block and continuous member with annular elements of the metering pump according to this invention in which an arrangement of various diameter axial bores and various materials of construction in conjunction with a continuous member with deformable annular elements enables fluid to be drawn into the pumping block from one external source and subsequently discharged to another external point without entering the pump housing.

Referring now to the drawings and particularly the one preferred embodiment as shown in FIG. 1, the invention comprises a pump housing 10 containing two sheaves 13 and 16 over which the continuous member 20 with annular elements 21 travels, and the pumping block 22. Sheave 13 is rigidly connected by means of a key 15 to a shaft 14 which extends outside the pump housing 10 and is rotationally driven by conventional means. Sheave 16 is mounted with a bushing 18 and is free to rotate about shaft 17, although sheave 16 may also be driven as sheave 13 as operating conditions warrant. A slack take-up and/or tensioning device for the continuous member may be provided but is not shown in the drawings. The fluid to be pumped or metered is introduced to the pump housing cavity 12 through a pipe or tubing connection 11. The volume of fluid thus introduced may be sufficient to cover the pumping block '22 or may fill the pump housing cavity 12 completely. A cavity filler block 19 may be used to reduce the internal volume of the pump housing cavity 12, or may be eliminated if it would be desirable to utilize the full volume of the pump housing cavity 12 as a fluid resevoir. The sheaves 13 and 16 and the pumping block 22 are arranged so that the track of the continuous member 20 with annular elements 21 coincides with the axis of the stepped bores 24 and through the pumping block 22.

Operating as a pump with the continuous member 20 travelling in the direction indicated by the arrow on sheave 13, a volume of the fluid in the pump housing cavity 12 which is maintained at a level above the pumping block 22 is drawn into the bore 24 and contained between successive annular elements 21 mounted on the continuous member 20, a seal being formed between the compressible annular elements 21 and the bore 24 wall. This volume of fluid is equal to 1r(R,, R (P) V, as previously defined. As the continuous member 20 moves past the transition area 29 into the smaller bore 25, a new volume is defined between any two successive annular elements 21 as 1r( R R (P) V. With the continuous member 20 with annular elements 21 moving at a velocity S, the net volume of fluid displaced in the transition area 29 between the two bores of different diameters will be equal to S1r( R R where the volume of each annular element is constant in the two bores. A further minor correction factor to this fluid volume due to a possible change in V, the volume of the annular elements 21, depending upon the design and construction materials, may be required as the annular elements 21 are further deformed and compressed moving from bore 24 with radius R to bore 25 with smaller radius R g.

One or more passageways to conduct the fluid being pumped are provided from the proximity of the transition area 29 to the outside of the pumping block 22. As shown in FIG. 1, two such passageways are provided, passageway 26 to conduct fluid displaced between bore 24 and the end of the slope in the transition area 29 adjacent to the bore 25 while an annular element 21 is in the transition area 29, and the passageway 27 to conduct displaced fluid between the end of the slope in the transition area 29 adjacent to the bore 24 and bore 25 while the annular element 21 is in the transition area I 29. Both passageways 26 and 27 are connected to a single discharge passageway 28 by means of a collecting fitting 23.

Reversing the direction of travel of the continuous member 20 with annular elements 21 and sheaves 13 and 16 will cause fluid to be drawn into the passageway 28 instead of being discharged, and the fluid will then mix with the fluid drawn from the pump housing cavity 12 through bore 25 and will subsequently be discharged back into the pump housing cavity 12 through bore 24.

Various alternative embodiments of the metering pump according to this invention are shown in FIGS. 2, 3, 4, 5, 6 and 7, specifically with regard to variations in the continuous member with annular elements and the pumping block. The pump housing and internal arrangement of the drive and other elements may be of a number of different configurations and orientations, their principal function being only to support, align and draw the continuous member with annular elements through the pumping block.

FIG. 2 shows a further embodiment of the pumping block and continuous member with annular elements wherein the continuous member 31a with annular elements 32 are molded of a resilient rubber of elastomeric material over a wire core 31b which provides resistence to longitudinal stresses encountered in drawing the continuous member 31a with annular elements 32 through the bores 36 and 37 of the pumping block 33. The pumping block in this embodiment consists of three elements for fabrication purposes, the pumping block housing 33, the entry bore tube 34 and the exit bore tube 35 separated some distance by a transition area chamber 38. A passageway 39 conducts the fluid displaced in the transition area to an external point of use according the relationship Sir-(R R as previously defined.

FIG. 3 shows another preferred embodiment of the pumping block assembly and continuous member with annular elements in which the continuous member 41 is a cable of high tensile strength and the annular elements 42 are rigid balls. The continuous cable 41 with rigid balls 42 is drawn through the axial bores 47 and 48 of the pumping block 44, and past the transition area 49 causing fluid to flow through passageway 50 connected to some external point of use in the manner previously described for FIGS. 1 and 2. The pumping block assembly consists of the pumping block housing 44, an end cap 45 connected to the pumping block housing 44 by screw threads or other means of adjusting the axial position of the end cap 45 in relation to the pumping block housing 44, a thrust washer 46, and a resilient rubber or elastomeric pumping block core 43. The entry bore 47 and the exit bore 48 of the pumping block core 43 are sized to be somewhat smaller than the diameter of the rigid balls 42, with the diameter of the exit bore 48 smaller than the diameter of the entry bore 47. The resilient material of the pumping block core 43 will therefore deform to permit the passage of the rigid balls 42, and form a seal between the rigid balls 42 and the walls of the axial bores 47 and 48. The volume defined between any two successive balls 42, the cable and the entry bore 47 wall is equal to 1r(R R (P) V+ C, where R,,, and R are the radii of the entry bore 47 and the cable 41 respectively, P is the pitch or longitudinal distance between annular elements 42, V is the volume of one annular element 42, and C is the volume of the deformed portion of the pumping block core 43 around each annular element 42 due to the structural nature and hysteresis of the material of the pumping block core 43. The volume defined between any two successive balls 42 in the exit bore 48 is as above with the substitution of R,,, as the radius of the exit bore 48 for R By longitudinally adjusting the position of the end cap 45 with respect to the pumping block housing 44, a compressive force will be transmitted to the pumping block core 43 through the thrust washer 46 causing the pumping block core to deform. Since the pumping block core 43 is externally restrained by the pumping block housing 44, such deformation will occur along the b bores and can be controlled and directed by the design of the pumping block housing 44 and pumping block core 43, the deformation in FIG. 3 occurring principally along the entry bore 47. By deforming the pumping block core 43 and reducing the diameter of the entry bore 47, the volume defined between any two successive balls 42, the cable 41 and the wall of the entry bore 47 can be changed. An extreme example of this change would occur when R the radius of the entry bore 47, is made smaller than R the radius of the exit bore, in which case the normal discharge flow of fluid through passageway 50 would be reversed with no change in the direction or continuous passage of the cable 41 with rigid balls 42 through the axial bores.

Referring now to FIG. 4 which is another preferred embodiment of the invention in which a deformable sleeve is utilized in the axial bore in conjunction with resilient annular elements 52 mounted on a continuous member 51 to achieve variable volume pumping. The operation is similar to the operations previously described in which the continuous member 51 with deformable annular elements 52 is drawn through a pumping block assembly with axial bores 58 and 59 of different diameters connected by a transition area 60. The pumping block assembly consists of a pumping block housing 53, an end cap 55 connected to the pumping block housing 53 by screw threads or other means, a retaining washer 54, a deformable sleeve 57, and a backing block 56 penetrated at regular intervals by passageways 61 into a fluid chamber 63 which is in turn connected to some external source of pressure by means of passageway 62 through the pumping block housing 53. Normal pumping operation is achieved in the manner previously described by the passage of the continuous member 51 with annular elements 52 carrying fluid to be pumped into the entry bore 58, of which the deformable sleeve 57 forms a portion, past the transition area 60 and through the exit bore 59, with the differential volume of fluid between that carried into the entry bore 58 and out of the exit bore 59 being discharged through passageways 64 in the pumping block housing 53. The fluid so discharged through the passageways 64 are collected in a manifold cavity 65 formed between the collecting fitting 66 and the pumping block housing 53 and are conducted to some external point of use through passageway 67 in the collecting fitting 66.

The volume of fluid to be pumped can be varied by introducing another hydraulic fluid or gas under pressure from some external resevoir through passageway 62 into the fluid chamber 63 and thence through passageways 61 causing the deformable sleeve 57 to deform in those sections where it is not otherwise restricted by the presence of annular elements 52 and to assume a configuration of reduced diameters and crosssectional areas. Thesereduced diameters and crosssectional areas of the deformed sections of the deformable sleeve 57 will thereby reduce the amount of fluid to be pumped being carried into the entry bore 58, and where the volume of fluid carried out through the exit bore remains essentially constant due to its constant diameter, the net volume of fluid being pumped will be reduced. The deformable sleeve 57 may alternatively be located in the section of the exit bore 59 adjacent to the transition area 60 to achieve a similar net effect on the volume of fluid to be pumped.

Two or more pumps may be connected in a series or parallel arrangement to achieve specific operating objectives, generally with the pumping blocks mounted within the same pump housing. FIG. 5 shows a further preferred embodiment of this invention with two rigid pumping blocks 73 and 81 on a common continuous member 71 with deformable annular elements 72, FIG. 5 being specifically designed for the accurate metering and pumping of fluids at pressures at which the fluids are compressible, but also representative of numerous possible configurations.

The operation of the pumping block 73 at FIG. 5 is as previously described for FIG. 1 wherein the continuous member 71 with deformable annular elements 72 carries a volume of fluid from the pump housing cavity, not specifically shown, into the entry bore 74 of the pumping block 73 and continues through the exit bore 75 of such pumping block, with the differential volume of fluid discharged through passageways 76 and 77 at each side of the transition area between the axial bores. The volume of fluid discharged through these passageways is conducted to and through a common passageway 78 and tubing 80 which connects to a passageway 86 and transition chamber in the pumping block 81, and also connects to the inlet passageway 96 of pressure control valve 94. The pressure control valve 94 functions to create a pressure in the transition chamber 85 approximately equal to the pressure in the discharge transition chamber 87 by directing the entire fluid flow from the pumping block 73 to the transition chamber 85 until the pressure in the transition chamber 85 and fluid tubing 80 slightly exceeds the fluid pressure in the discharge transition chamber 87 and passageway 88 communicating with one side of the diaphragm seal of the pressure control valve 94. When the pressure in the transition chamber 85 and fluid tubing 80 exceeds the pressure of the discharge transition chamber 87, the diaphragm 95 is displaced sufficiently to open passageway 97 in tubing 98, permitting excess fluid from pumping block 73 to flow through the pressure control valve 94 and be returned to the fluid resevoir in the pump housing cavity, this function being performed on a continuous and modulating basis.

The continuous member 71 with annular elements 72 carries fluid to be pumped into the entry bore 82 of pumping block 81, through the intermediate bore 83, and continues through the exit bore 84, with the entry bore 82 and intermediate 83 being of the same diameter, and of a greater diameter than the exit bore 84. The fluid carried through the entry bore 82 is augmented in the transition chamber 85 by fluid from the pumping block 73 at a pressure approximately equal to the pressure in the discharge transition chamber 87, and any additional fluid required due to compressibility of the fluid to maintain a specified volume is provided by the fluid from pumping block 73, the excess of such fluid being returned to the resevoir in the pump housing cavity as previously described. The continuous member 71 with annular elements 72 therefore merely meters the required volume of fluid to be pumped by transporting such fluid through the intermediate bore 83 between two cavities at approximately equal pressure according to the relationship S1r(R,, R also as previously defined. A portion of the fluid thus transported through the intermediate bore 83 is removed from the pumping block 81 through exit bore 84 in the now familiar manner, with the differential volume of fluid being discharged through passageways and 91 in the pumping block 81 and thence through passageway 93 in the collecting fitting 92 to some external point of use. All calculations for these fluid volumes must include factors for the compressibility of the fluid and, under certain conditions, for the deformability of the continuous member 71, annular elements 72 and pumping block 81.

Further modified forms of the pumping and metering device according to this invention can be suitable for a variety of operating requirements. FIG. 6 shows a preferred embodiment of the continuous member 101 with annular elements 102 and pumping block 103 configuration for metering, mixing and pumping defined volumes of two separate fluids to some external point of use. The continuous member 101 with deformable annular elements 102 is drawn through the axial bores of a pumping block assembly consisting of the pumping block 103, end cap 104 secured to the pumping block, deformable sleeve 105 and sleeve supporting ring 106. The diameter of the entry bore 107 is sized to be sufficiently greater than the diameter of the continuous member that fluid will be carried into the entry bore 107 by the passage of the continuous member 101 with annular elements 102. The intermediate bore is of greater diameter than the entry bore 107, but of small enough diameter to form a contact seal with the annular elements 102. The exit bore for the pumping block assembly is formed by the deformable sleeve 105, the inside diameter of which is slightly smaller than the diameter of the continuous member 101 in order to form a sufficiently tight seal between the deformable sleeve 105, the continuous member 101 and the deformable annular elements 102 that negligible amounts of fluid will be carried out of the pumping block assembly through the exit bore. The continuous member 101 with annular elements 102 will carry an amount of fluid into the entry bore 107 equal to S'rr(R R NV. The amount of fluid transported through the intermediate bore 110 is equal to S1r(R;, R NV and, as this is greater than the volume carried into the entry bore 107, fluid from some external source will be conducted through passageway 109 to mix with the fluid carried through the entry bore 107 in the transition chamber 108. This fluid mixture is transported through the intermediate bore 110 into the discharge transition chamber 111 and completely discharged to some external point of use through passageway 112 since negligible fluid is carried out the exit bore through the deformable sleeve 105 as previously described.

Yet another preferred embodiment of the pumping block assembly and continuous member with annular elements according to this invention is shown in FIG. 7 to provide means of metering and pumping a fluid without having such fluid within the pump housing cavity, previously defined. The pumping block assembly consists of a pumping block housing 123, end caps 124 and 125, deformable sleeves 126 and 128, and supporting rings 127 and 129. The deformable sleeves 126 and 128 at each end of the pumping block housing 123 are sized to form a sufficiently tight seal with the continuous member 121 with annular elements 122 that negligible amounts of fluids or gases will be carried into or out of the pumping block housing as described above for FIG. 6. Where the intermediate bore 132 of the pumping block housing 123 is of slightly smaller diame ter than the diameter of the annular elements 122 thereby forming a contact seal with such annular elements, the passage of the continuous member 121 with annular elements 122 will cause fluid to be drawn in to the transition chamber 130 through passageway 131 from some outside source, be transported through the intermediate bore 132 into the discharge transition chamber 133, and thence discharged to some external point of use through passageway 134.

The present embodiments of the invention herein described in the specification and shown in the drawings are only illustrative. Many further modifications to the form and to the type of apparatus employing some configurations of the pumping body and continuous member with annular portions can be made, and the invention can be used in other devices such as meters, compressors, and the like as well as the basic transport for chemical analysis equipment as mentioned above.

In an even broader sense, the invention may be employed in devices where the fluid being pumped or metered is contained in cavities in the exterior of a continuous member which is drawn through the section of a bore where the cross-section of the bore changes. The member which carries the cavities need not be circular in cross-section and the cavities may be defined as discreet cavities in the exterior surface of the member rather than the space between the annular elements mentioned above. Additionally, the member which carries the pumping cavities need not be endless but merely continuous in the area of the elongated passageway.

For instance, the apparatus may be formed in a manner similar to that shown in FIG. 1 where the circular elements 13 and 16 are not merely drive pulleys for an endless member but instead spools on which a finite length of a continuous member is wound, and the continuous member may, for instance, take the form of a nonstretc hable metal core with a resiliently deformable covering thereon similar in many respects to the structure shown in FIG. 7 while the pumping cavities may be merely circular or irregularly shaped depressions in the resiliently deformable covering.

Similarly, the resiliently deformable material which permits the cavities to change in volume as the member moves through the transitionary area may form a part of the cavity walls instead of or in addition to the use of resiliently deformable material in the movable member itself.

What is claimed is:

1. Apparatus for metering small volumes of fluids which comprises:

A. Body means having an elongated passageway therein with said passageway having a smaller portion of smaller cross-sectional area, and a larger portion of larger cross-sectional area and a transitionary portion therebetween,

B. An endless member extending longitudinally through said passageway and movable longitudinally therethrough,

C. A plurality of annular portions attached to said endless member for movement therewith through said passageway with said annular portions being engageable with said passageway, in fluid sealing relation in both said first and second portions,

D. First fluid flow means communicating with said passageway adjacent to said transitionary portion, and

E. Second fluid flow means communicating with the larger portion of the passageway.

2. The apparatus of claim 1 characterized further by the inclusion of drive means for moving said endless member along its length from said larger portion of said passageway hence through said transitionary portion and hence through said smaller portion for metering fluid from said second fluid flow means to said first fluid flow means.

3. The apparatus of claim 1 characterized further by the inclusion of drive means for moving said endless member along its length from said smaller portion of said passageway hence through said transitionary portion and hence through said larger portion for metering fluid from said first fluid flow means to said second fluid flow means.

4. The apparatus of claim 1 in which said annular portions of said endless member are made of a resiliently deformable material and said endless member is made of a substantially unstretchable material.

5. Apparatus for metering small volumes of fluids which comprises:

A. Body means having an elongated passageway therein with said passageway having a smaller portion of smaller cross-sectional area, and a larger portion of larger cross-sectional area and a transitionary portion between,

B. An endless member extending longitudinally through said passageway and movable longitudinally therethrough,

C. A plurality of annular portions attached to said endless member for movement therewith through said passageway with said annular portions being engagable with said passageway in fluid sealing relation in both said first and second portions,

10 D. First fluid flow means communicatingwith said passageway adjacent to said transitionary portion, and E. Second fluid flow means communicating with the 5 larger portion of the passageway.

in which said endless member is made of a substantially unstretchable material, said annular portions of said endless member are made of substantially rigid material, and said body means is made of a resiliently deformable material in that portion of said body means surrounding said smaller portion of said passageway.

6. The apparatus of claim 1 in which said larger portion of said passageway has a diameter larger than the diameter of said endless member but less than the diameter of said annular. portions, and said second fluid flow means surrounds said endless member.

7. The apparatus of claim 1 in which both said larger and smaller portions of said passageway have diameters larger than the diameter of said endless member and smaller than the diameter of said annular portion.

8. The apparatus of claim 5 in which said body means includes a substantially rigid housing, a resiliently deformable passageway, and means for compressing said resiliently deformable portion axially of said passageway to change the cross-sectional area of said passageway.

9. The apparatus of claim 1 characterized further by the inclusion of a flexible membrane in said body means forming a wall of one of said portion of said passageway and means for pressurizing said body to deform said membrane and thereby change the cross-sectional area of said passageway adjacent thereto.

10. Apparatus for metering small volumes of fluids which comprises:

A. Body means having an elongated passageway therein with said passageway having a smaller portion of smaller cross-section areas, and a larger portion of larger cross-sectional area and a transitionary portion therebetween,

B. An alongated member extending longitudinally through said passageway and movable longitudinally therethrough,

C. A plurality of spaced apart fluid cavities in the exterior of the endless member movable therewith through said passageway,

D. Resiliently deformable means adjacent to said fluid cavities for permitting said fluid cavities to change in volume where said elongated member passes through said transitionary portion of said passageway,

E. First fluid flow means communicating with said passageway adjacent to said transitionary portion, and

F. Second fluid flow means communicating with the larger portion of the passageway.

11. The apparatus of claim in which said resiliently deformablemeans comprises a portion of said elongated member.

12. The apparatus of claim 10 in which said resil- 60 iently deformable means comprises a portion of said body means. 

1. Apparatus for metering small volumes of fluids which comprises: A. Body means having an elongated passageway therein with said passageway having a smaller portion of smaller cross-sectional area, and a larger portion of larger cross-sectional area and a transitionary portion therebetween, B. An endless member extending longitudinally through said passageway and movable longitudinally therethrough, C. A plurality of annular portions attached to said endless member for movement therewith through said passageway with said annular portions being engagable with said passageway in fluid sealing relation in both said first and second portions, D. First fluid flow means communicating with said passageway adjacent to said transitionary portion, and E. Second fluid flow means communicating with the larger portion of the passageway.
 2. The apparatus of claim 1 characterized further by the inclusion of drive means for moving said endless member along its length from said larger portion of said passageway hence through said transitionary portion and hence through said smaller portion for metering fluid from said second fluid flow means to said first fluid flow means.
 3. The apparatus of claim 1 characterized further by the inclusion of drive means for moving said endless member along its length from said smaller portion of said passageway hence through said transitionary portion and hence through said larger portion for metering fluid from said first fluid flow means to said second fluid flow means.
 4. The apparatus of claim 1 in which said annular portions of said endless member are made of a resiliently deformable material and said endless member is made of a substantially unstretchable material.
 5. Apparatus for metering small volumes of fluids which comprises: A. Body means having an elongated passageway therein with said passageway having a smaller portion of smaller cross-sectional area, and a larger portion of larger cross-sectional area and a transitionary portion between, B. An endless member extending longitudinally through said passageway and movable longitudinally therethrough, C. A plurality of annular portions attached to said endless member for movement therewith through said passageway with said annular portions being engagable with said passageway in fluid sealing relation in boTh said first and second portions, D. First fluid flow means communicating with said passageway adjacent to said transitionary portion, and E. Second fluid flow means communicating with the larger portion of the passageway. in which said endless member is made of a substantially unstretchable material, said annular portions of said endless member are made of substantially rigid material, and said body means is made of a resiliently deformable material in that portion of said body means surrounding said smaller portion of said passageway.
 6. The apparatus of claim 1 in which said larger portion of said passageway has a diameter larger than the diameter of said endless member but less than the diameter of said annular portions, and said second fluid flow means surrounds said endless member.
 7. The apparatus of claim 1 in which both said larger and smaller portions of said passageway have diameters larger than the diameter of said endless member and smaller than the diameter of said annular portion.
 8. The apparatus of claim 5 in which said body means includes a substantially rigid housing, a resiliently deformable passageway, and means for compressing said resiliently deformable portion axially of said passageway to change the cross-sectional area of said passageway.
 9. The apparatus of claim 1 characterized further by the inclusion of a flexible membrane in said body means forming a wall of one of said portion of said passageway and means for pressurizing said body to deform said membrane and thereby change the cross-sectional area of said passageway adjacent thereto.
 10. Apparatus for metering small volumes of fluids which comprises: A. Body means having an elongated passageway therein with said passageway having a smaller portion of smaller cross-section areas, and a larger portion of larger cross-sectional area and a transitionary portion therebetween, B. An alongated member extending longitudinally through said passageway and movable longitudinally therethrough, C. A plurality of spaced apart fluid cavities in the exterior of the endless member movable therewith through said passageway, D. Resiliently deformable means adjacent to said fluid cavities for permitting said fluid cavities to change in volume where said elongated member passes through said transitionary portion of said passageway, E. First fluid flow means communicating with said passageway adjacent to said transitionary portion, and F. Second fluid flow means communicating with the larger portion of the passageway.
 11. The apparatus of claim 10 in which said resiliently deformable means comprises a portion of said elongated member.
 12. The apparatus of claim 10 in which said resiliently deformable means comprises a portion of said body means. 